288 
Notes . 
Sugars — 
Cane-sugar 
A. 
per cent. 
B. 
per cent. 
Dextrose 
Levulose 
Maltose 
9.98 3-49 
0-00 0*58 
1 41 3.46 
2-25 i-86 
Total sugars per cent. 13*64 9-39 
By the constant repetition of experiments such as those mentioned 
we have been able to arrive at certain definite conclusions of im- 
portance. 
In the first place, our experiments are decidedly opposed to the 
view that either dextrose or levulose is the first sugar formed by 
assimilation, at any rate in the leaves of Tropaeolum. They point, 
however, to cane-sugar as being the first distinctly recognizable 
sugar to be synthesized by the assimilatory processes. 
There seems every reason to believe that this cane-sugar, which 
may be regarded as the starting-point of all the metabolic changes 
taking place in the leaf, accumulates in the cell-sap of the leaf- 
parenchyma when assimilation is proceeding vigorously. When the 
concentration exceeds a certain point, starch commences to be 
elaborated by the chloroplasts at the expense of the cane-sugar. This 
starch forms a somewhat more stable reserve substance than the 
cane-sugar, and is only drawn upon when the more readily meta- 
bolized cane-sugar has been partially used up. 
That the starch which is formed in the chloroplasts is, strictly 
speaking, not autochthonous, but owes its origin to antecedent 
cane-sugar, seemed probable, not only from a consideration of the 
results we have described in the paper, but also from Boehm’s and 
Meyer’s experiments on the artificial nutrition of leaves by solutions 
of certain carbohydrates, and also from results which we obtained 
and described in 1890 on the starch-producing powers of some of 
the sugars when used as a nutrient for embryos of the Grasses. 
In all these cases it was found that cane-sugar surpasses all other 
carbohydrates in starch forming. 
As regards the particular form in which the carbohydrates wander 
from cell to cell in the leaf and finally enter the stem, we think 
our experiments warrant us in the statement that the cane-sugar 
is translocated as dextrose and levulose, and the starch as maltose, 
